Memory cell array biasing method and a semiconductor memory device

Abstract

A method of biasing a memory cell array during a data writing operation and a semiconductor memory device are provided. The semiconductor memory device includes: a memory cell array including a plurality of memory cells in which a first terminal of a memory cell is connected to a corresponding first line among a plurality of first lines and a second terminal of a memory cell is connected to a corresponding second line among a plurality of second lines; and a bias circuit for biasing a selected second line to a first voltage and non-selected second lines to a second voltage.

Description

CROSS-REFERENCE TO RELATED APPLICATION[0001]This application claims priority to Korean Patent Application No. 10-2005-0006581, filed on Jan. 25, 2005, in the Korean Intellectual Property Office, the disclosure of which is incorporated by reference herein in its entirety.BACKGROUND OF THE INVENTION[0002]1. Technical Field[0003]The present invention relates to a semiconductor memory device, and more particularly, to a semiconductor memory device and a data writing method for controlling a biasing level of a memory cell array.[0004]2. Discussion of the Related Art[0005]Phase change random access memories (PRAMs) are nonvolatile memory devices which store data using a phase change material, e.g., Ge—Sb—Te (GST), whose resistance changes in accordance with a phase transition due to a change in temperature.[0006]FIG. 1 illustrates an equivalent circuit of a unit cell C of a PRAM. Referring to FIG. 1, the unit cell C consists of a P—N diode D and a phase change material GST. The phase chan...

AI Technical Summary

Benefits of technology

[0016]A semiconductor memory device and a data writing method are provided that prevent current from flowing from a selected bit line to a non-selected word line by maintaining a constant voltage in the non-selected word line, thereby enabling stable sensing and increasing the operating speed of the semiconductor memory device.

Problems solved by technology

However, since the word lines WL0, WL1, and WL2 have a high resistance, the number of unit cells connected to the word lines WL0, WL1, and WL2 is limited.

Since current may flow through unselected word lines that are floating, it is difficult to increase the operating speed of the semiconductor memory device and perform stable sensing.

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